A. S. Mokhtar

Shelf life assessment of MalaysianPangasius sutchi during cold storage

The findings of the present work yield useful information about the MalaysianPangasius sutchi concerning the marketing sector from the point of view of shelf life and storage temperature in the range of 0 to 10‡C. A fresh batch of typical samples, were stored similarly in four chillers of different temperatures for a period of 28 days. During the course of storage, the samples were periodically subjected to pH and sensory tests performed by trained panelists. Experimental observations were analysed and regressed to develop three correlations. The first one was between the sensory tests and the storage time and temperatures, while the second one related pH values to storage time and temperatures. Finally, a correlation between sensorial and pH values was developed as well. The first correlation is presented in tabular form to yield a simple guide to fish retailers, by which quality and shelf life of the displayed fish commodity may be estimated.

Solution of Navier‐Stokes equations by fourth‐order compact schemes and AUSM flux splitting

Purpose – To develop a high‐order compact finite‐difference method for solving flow problems containing shock waves.Design/methodology/approach – A numerical algorithm based on high‐order compact finite‐difference schemes is developed for solving Navier‐Stokes equations in two‐dimensional space. The convective flux terms are discretized by using advection upstream splitting method (AUSM). The developed method is then used to compute some example laminar flow problems. The problems considered have a range of Mach number that corresponds to subsonic incompressible flow to hypersonic compressible flows that contain shock waves and shock/boundary‐layer interaction.Findings – The paper shows that the AUSM flux splitting and high‐order compact finite‐difference methods can be used accurately and robustly in resolving shear layers and capturing shock waves. The highly diffusive nature of conventional flux splitting especially on coarse grids makes them inaccurate for boundary layers even with high‐order discreti...

Flux Limiting with High-Order Compact Schemes

In this paper, we present a modified flux limiter for limiting the numerical flux differences obtained from a fifth-order upwind compact scheme. The accuracy of the scheme is tested through the solution of the scalar 1D inviscid Burgers equation. The method is then used for solving the 2D Euler equations for flows containing shocks. For unsteady problems, a multistage SSP Runge-Kutta method is employed for the time integration. For twodimensional steady-state solutions, first-order implicit time integration, with LU decomposition, is employed. Results have shown that the developed flux limiter significantly eliminates the numerical oscillations.

An AUSM‐based high‐order compact method for solving Navier‐Stokes equations

A high‐order compact upwind algorithm is developed for solving Navier‐Stokes equations in two‐space dimensions. The method is based on advection upstream splitting method and fourth‐order compact finite‐difference schemes. The convection flux terms of the Navier‐Stokes equations are discretized by a compact cell‐centered differencing scheme while the diffusion flux terms are discretized by a central fourth‐order compact scheme. The midpoint values of the flux functions required by the cell‐centered compact scheme are determined by a fourth‐order MUSCL approach. For steady‐state solutions; first‐order implicit time integration, with LU decomposition, is employed. Computed results for a laminar flow past a flat plate and the problem of shock‐wave boundary layer interaction are presented.

Significance of Solar Radiation on Aircraft Engine Under Cowl Temperature

Literature on solar radiation effect on aircraft engine under cowl temperature is very limited. This paper describes an experimental work to quantify the effect of solar radiation levels on a range of aircraft engine nacelle surface finish and orientation in a representative way. The investigation was carried out on four aircraft engine nacelle representations during static ground running conditions. The nacelle models were fabricated using aluminium and surface coated with four different aircraft paint finish. Thermocouples were mounted at locations around the nacelle model. Effects of different solar radiation levels on the temperature distributions on the nacelles were presented. The contributions of radiative and convective heat transfer on the overall distribution of temperature inside the under cowl were quantified.Copyright

Thermal Diffusivity Variation Study of Cold Stored Malaysian Pangasius Sutchi at 10°C

This paper presents the use of thermal diffusivity-variation of Malaysian Pangasius Sutchi freshwater fish as a criterion to estimate the freshness in fish marketing. A homogenous specified area of a fresh fish body was cut into slices which were wrapped and preserved in a cold store of 10°C for a period of 28 days. Ansaris approach has been found earlier as an appropriate one to measure the thermal diffusivity of fish through transient cooling. The daily measurement of those slices (samples) along the muscle orientation revealed that thermal diffusivity increased up to 3 days then stayed approximately constant up to the end of the preservation period (28 days). In the literature the shelf life was also found 3 days at 10°C, which in turn agreed with the present investigation. Regression analysis was made to develop an empirical correlation between thermal diffusivity ratio and preservation time of the fish under study. This correlation could be used by food technologists as an index of deterioration of freshness or consumer acceptance